Production of Trioxane from Formaldehyde via Hierarchical Beta Zeolite Synthesized Using a Cationic Polymer

Trioxane (TOX), which is usually produced from formaldehyde catalyzed by acid-catalysts, is an important polymerizing monomer to produce high-performance plastics polyoxymethylene polymers (POMs). In order to reduce the separation cost and increase the catalytic activity, hierarchical Beta zeolites with different pore size were synthesized by PDDA and used for TOX produce from formaldehyde in this work. Hierarchical Beta zeolites’ average pore size increased with the increasing of PDDAs’ molecular weight. Compare to conventional Beta zeolite, it exhibited a higher catalytic performance with 95.13% selectivity and 2118 g/kg/h space–time yield of TOX due to its excellent diffusion performance from extra mesopore. The HCHO conversion and space–time yield of TOX increase first and then decrease with the pore size increasing. Further research showed that the decrease of catalytic activity is mainly due to the increase of extra-framework Al percent. This work illustrates the influence of both pore size and extra-framework Al content in hierarchical Beta zeolites for TOX produce from formaldehyde reaction. Graphical Abstract